Index Tiff Question

[mootpointilism]

Hello all—

I am a Graphic Designer. (which may be shorthand for "consider this an extremely ignorant question"). I have received some index tiffs from a client and I am attempting to match the 3 or 4 colors in it's table to some specific CMYK values. Our process for this has so far been to convert the Index tiff to CMYK and use "Select color range" and eyedropper to select and then change the CMYK values used in the image. That has worked out well except that when the image contains more than 3 or 4 colors, correcting each one in this fashion can add up, especially when this is the process we are using for 100s of images.

In an attempt to speed up our processes I tried another method of color correcting the index tiffs. While the image is still in index mode I select the Color Table from the Image/Mode menu item (Photoshop CS3) and individually change the index colors' CMYK values. The problem I run into however (as you might be able to guess) is that when the index tiff is then converted from index mode to CMYK it shifts the CMYK values (presumably because the conversion it is based in RGB?)

My question then becomes:
Is there any way to convert an index moded tiff to CMYK mode and force the tiff to recognize and retain the CMYK values? A plug in perhaps, or magic spell?

I apologize if this is mind numbingly ignorant. I'm just looking for a way to save time color correcting these guys. I was hoping I had stumbled upon something.

Thank you for the bother!

-Bruce

[Louis Dery]

My question then becomes:
Is there any way to convert an index moded tiff to CMYK mode and force the tiff to recognize and retain the CMYK values? A plug in perhaps, or magic spell?

-Bruce

Hi Bruce,
Why not converting to RGB (sRGB or else), make corrections if needed (while using CMYK proofing simulation) and finally convert to CMYK.

Louis

[Lukas Engqvist]

Either way you should be able to create a photoshop action, wich means you can batch the process, especially if it is a select colour range fill with CMYK, select next colour range etc. Just make sure you have an image containing all possible colours when you make the action.
Recording takes the time of making one conversion, then batch the others n take a coffe while the machine works for you that's what machines are for.

[mootpointilism]

Am I correct in assuming that most 4-color printers cannot print an index tiff? It must be converted first for the CMYK values to be honored?

Thank you for the responses! The color pallet that I am referencing for CC is pretty expansive and not all index tiffs require all the colors in the pallet. So when I change colors in the color table it has to be done manually. But that process is quicker than converting to CMYK and doing a "Select/Color range" for all the individual colors. The way the color table is set up in PS for an indexed file is just quicker and more easily editable so I was hoping to find a way to use that in my workflow...

[Lukas Engqvist]

Never tried, should thinkn if you place in InDesign and you can make a PDF all will work fine. If you stay indexed that would be scriptable too.

Did a simple test and seems no problems using indexed colours if you place in InDesign and export to PDFx. In the PDF the image is no longer indexed.

It's probably not that it can't be done, just that I haven't done it (knowingly) before.

[mattbeals]

Indexed TIFF, indexed JPEG, indexed GIF if shouldn't matter. Indexing is basically a lossless form of image compression. What is of significance is the underlying color space; RGB, CMYK or gray scale.